Telephone-exchange system.



H. BROWNE, TELEPHONE EXCHANGE SYSTEM.

APPLIGATION FILED DBG. 19, 1904. 'ly;z;p% Y Patented 5311.26, 1915.

5 SHEETS-SHEET l.

S. H. BROWNE.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION HLED'DEG.19,1904.

1,125,954, l Patented 1111.26, 1915.

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S. E. BROWNE. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEG. 19, 1904. Llp, l Patented 531126,1915.

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S. H. BROWNE. TELEPHONB EXCHANGE SYSTEM. APPLICATION FILED DEG.19, 1904.

1,125,954. Panam Jan. 2g, ma.

www??? L BROWN, TELEPHONE EXCHANGE SYSTEM.

APPLIQATIOH FILED DEO. 19, 1904. Lm. v Emma Jan. 2%, 19m.

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To elli'whofm, it may concern Be it known that I, Snmnr HAND Bnowivn,

`a citizen vof the United States of America,

and resident of Pittsburgh, county of Allegheny, aii'dState of Pennsylvania, have/iu vented v'apn wgand useful improvement in Telephdnelfx'cliange Systems, of which the following isb specification.

- `My invention relates to improvements yin telephone exchange systems, and has for its object the quickening of telephone service and a lowering of the cost thereof by de creasing the number of operators, or the number ofrhours voftlneir work, or both.

The invention relates more particularly to an improved system of receiving and disi "tributing incoming vcalls whereby such calls are grouped uponreceipt and forwarded' to4 the attendant telephone operators insuclimanner asto be most advantageously and economically handled by the operators.

In telephone exchanges of the most general use, which therefore may be termed of.

*he most modern accepted type, a line signal is associated at the central station with each telephone line, for the purpose of indicating the calls coming in over -such line from the substation or substations thereof; so that whenever a substation of any particular line transinits a call, the particular line Vsignal Vamong the different parts or divisions of the switchboard. rlhe distribution therefore becomes such that certain -line signals are said to belong' to a certain operators position, and all calls originating upon the lines connected with thoseline signals are re- `ceived upon that operatorsposition of the switchboardk and require to be answered from that position. As dierent lines will v show differing amounts of business during the day, an inequality of the distribution of Specicationof'lietters Patent; t

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Patent-@dl Jaime 26, llglila application filed meemaaie, iena semaine. esatta. A M i work amongoperators will naturall'yjresult, and this inequality will result from 'two vai-L i tations: first, the differing amounts of'busi ness or number of calls from one line or group of lines as 'compared with other lines or groups of lines, and, second, vthedieriurig amounts of business or number" of calls'fom' any line or y,s ,rfroup of lines during one period of time as compared with the business or number of calls received from the same line or group of lines during' an equal'period of o. I time at some other hour of the day or night.

The duties of an operator' sitting before a group of line signals therefore vary considerably, and these Vvariations have been contended with separately in the prior: and present state of the art.

To overcome the unequal distribution of labor among operators by reason of one po-l sition having a large number of busy lines while another position has a. small number of comparatively idle lines, the intermediate distributing frame has been invented and l used generally, bymeans of which itis possible to change any line on ther switchboard to the service of any operator on the switchboard, and thus to give to each operator her due proportion of the busy lines and also hei'v "eqnalizing their duties; and also when xop- :portune to distribute the entire dutiesof the exchange upon a smallernumber .of operators, l

thus reducing the operating force and work' ing economy in operating. But' in all of these distributions by means of the intermediate distributing frame the load of' the busiest hour must be considered and provided for that no operator may be overbur-` dened at that time to the detriment ofthe service given to any particular call. This 'distribution by means of the intermediate distributing frame therefore utilivies 100 perl cent.I of 'an operators ability 'during the i hours of heavy traflic ofthe day, but necessarily entails occupying her du'ringfthe remaining hours 'of her .daily service with less labor than she couldhandle eiiiciently and economically.

ion

To overcomev the unequal distribution of the calls throughout the day and night, it is the common practice to provide uniform equipment throughout the switchboard for all lines and for all operators, and to place the operators positions near each other so that the tools with which any operator works may be used to answercallsupon the position on either side of her as well as upon her own. This permits relieving onehalf of the operators when the traic falls below 50 per cent. of each operators capacity, and permits relievin two-thirds of the operators when the tra c falls below 33% per cent. of each operators capacity, but beyond this limit the plan is ineffectual, as with the present practice in telephone switchboards an operator sitting ather position cannot reach more than three positions including her own. Even with this arrangement of economy in number of operators working, the loss in operating eiliciency is large during such hours as will give to each operator duties between 50 and 100 per cent. of her capacity or between334. and 50 per cent.7 or less than 33?; per cent.

At night, in a large exchange, when the operating load falls to less than one per cent. of the heaviest day load, one loperator should handle 100 operators positions; but this is rendered difficult by the fact that the calls still continue to come in upon line signals distributed all over the extent of the switchboard and the operator necessarily would have to walk to each line signal to answer that call. The loss of time to the operator and the delay to each call may be so great as to justify'the employment of two or even more operators for a task which lies well within the capacity of one operator, could the calls be eiiicently and economically brought to her. It is with this double problem of the distributionr of operating load upon operators that my invention deals. It is the theory of my invention to receive all calls upon automatic apparatus or switches v connected permanently with the lines andgrouped in one group or in two or more closely related groups; to forward from these automatic apparatus or switches tothe 'first operator on duty as many calls as she can handle efiiciently; if a surplus of calls over the first operators capacity exists, tlien to forward to the second operator on duty as many calls as she can handle eiiiciently; and thus to continue with successive operators, sending all calls received promptly and directly to the switchboard, and sendin each call received to a line signal locate before a waiting operator, whether the traff fic of the exchange at that moment be occupying the efforts of only one operator or of a very large number of operators.

In1 Patent' No. 1,07 3,589 issued September 23, 1913, upon my prior application, No.

struction of trunks such as are suitable for utilization in the system of my present invention, which latter deals more particularly with the arrangement of the trunks among themselves, with the arrangement of the trunk terminals upon the switchboard, and with the arrangement of the trunk terminals at the automatic switches which belong to the telephone lines.

My said prior application, as filed, contained in its descriptiona disclosure of the subject-matter of many of the claims herein.

In the drawings- Figure 1 showsdiagrammatically the circuits and apparatus of a trunk such as described and illustrated in my application above mentioned. Fig. 2 shows the method of distribution of calling elements in an office requiring but one set of automatic switches with one group of trunks, there being shown only a limited number of telephone lines and associated trunking elements. Fig. 3 shows the method of distribution of calling elements in an olice too large to'handle all business over one group of trunks. Both Fig. 2 and Fig. 3 show the elements in ultimate simplicity. Fig. 4 shows the method of distribution of calling elements in an oiice with distributing frames lending convenience and flexibility to the system. Fig. 5 is a plan View, Fig. 6, an elevation, and Fig. 7 a horizontal section, on line 7-7 of Fig. 6, of an automatic switch uitable for connection with each telephone ine.

Fig. 1 shows two telephone lines, 41 and 41, with their substation telephones 43 and 43, and their connected multiple jacks, 44-44 and 44a-44B. Each line is assumed distributinv device, which is indicated only at 98 for line 41, but is shown in full diagrammatically for line 41. 100 is an automatic switch', consisting of fixed and rotary parts carrying fixed and rotary contact points, respectively. It is the duty of the automatic switch to move the set of rotary contacts over the fixed contacts, successively, until a suitable set of fixed contacts is found; then to permit the rotary contacts to remainupon that set of fixed contacts until disconnection is desired. Because of this action of the rotary contacts moving forward to select specific fixed contacts, therot-ary contacts are hereafter designated selecting contacts, or wipers, and the fixed contacts, waiti'g for the selecting contacts to approach them, are hereafter called waiting contacts. The rotary contacts are one set of four, shown in Fig. 1

, at 34, 35, 36 and 37. The waiting contacts are -mmany sets of four each, one set 28h, 27.", 26", 25 being shcwn near the selecting meente The magnet 1 with its armature enel 'ratchet Wheel is designe@ to propel seid rotary wrt of snirl automatic switch, and

Athereby to 'propel seid?. selecitingn contacts `fiber, is clem which stand normally disconnecteol from any Waiting contsetsn @non the iirst energisetion oi magnet l., seiol selecting contacts are propelled into Contact with set 28E", 2W, 265, 25 of the waiting contects; then :it the next energization oliniegnetl troni the preceding set enel into Contact with set 2B, 27E, iti enti 95C, etc. Magnet 8 is elesignecl to release the rotary part ot szii switch, Wherenpon, by the notion ot the spiral spring 1&1 shown connected with ratchet Wheel 13, the entire rotary peri, oi" the automatic switch is retnrnel to its position ot rest the selooting Wipers thus elise-cnneci'zesll from any Waiting contact-s.

A suitable automatic switch, such es that reterrecl to above, is illustre-ted more in (letail in Figs. 5, ti enfl'?. The plates 23 enti 2A, hei/ing the lugs 4&0, et@ formeel troni them tor convenience in mounting the switch, are Clampett together by the holte titl enel the nuts 30. fontaet pieces 25h, 26, 27, 28 constituting one group, 25, 26e, 27', 23 en other group, 25, 2%' enel 28X another group, enti so on,-sre arranged in four horizontal circuler eres lbetween the plates 23 and 2st.; inthe torni of switchwhich l have here shown, there are twenty-tive contact pieces in each are, enel each piece is lai-ought out. at the periphery of the circular `portion ot the switch so that e wire may he uttechecl to enchrow ot contact pieces snel the neighboring row, between the upper ronT and the top jolt-ite 2t, en between thelower row enel the bottom plate 2B, insuleting in fini sneh es corel rubber or peel oy 'the bolts 38, enel the screws 955. This serves the double purpose of inseln-ting the content pieces from each `other :intl from the framework, enel holding ell et 'th-ein `securely in position.

"Plates 23 and 2e? here thereon. bearing studs enel 29 respectively, which gfiiiole enel support the vertical shaft 3@ carrying at its upper enel the ratchet Wheel 13, adepte'cl to be hohl in or returned norme-l position by the action oit the spiral spring 1t,

attached to the shaft :it one end, and to 'the pin 15 et its other enel. The pin 15 is corrieri by the top plete 1'Vi/"hen the ratchet 1:2 'feel in its normal position the pin 22 engagesthe post 16, and also engages the Contact spring 19, bending the latter ont of engagement with thev Contact piece 18. rlhe spring .19 carries on its end en insulation to prevent electrical. Contact with the pin E22. Spring 19 and the piece 18 are separated :troni electrical contact with each other and with the conducting part of the switch structure, by the insulating ieces QU, Q enel 20h, or" rubber or other suitable materiel they are bound to place by a vscrew 2l, hushed from Contact with the spring and contact piece in o familiar manner, and entering the bracket 12. rEhe bracket 12 serves the double purpose of supporting the mag'- net coils 8 and 8, intl of forming e part of the magnetic circuit of those coils. A retaining pewl 10 :tor the ratchet Wheel 13 is pivoteol to the brochet. Helical spring 11 holds the pawl 10 in engagement with a tooth of the ratchet wheel 13, exe t when the cores ot the coils 8 enel 8a are su ciently energized to attract the iron armature 9.

lhe magnet Jtermed of the coils 1 and 1a is oit very similar construction, having the bracket 2, the iron armature l, the lever 8 Fim-and o helical retractile spring 7 `which tends not only normally to hold the firm and armature 3 und 4 respectlvely, sway `from the cores ot the coils'l and la, but

`:i1-1n 5 will enable it, While still sliding in Contact with the post 6, to engage a tooth ot the ratchet Wheel 13 and advance the wheel one step, the Wheel being held in its advanced position by pswl l0. lVhen the cores 1 and 1a are (lenergized, the tip of the :irin 5 will again pass out of engagement with the ratchet wheel 13; hence successive impulses of current will advance the ratchet wheel step by. step, carrying with it the shaft 30. The relation between the teeth ot' the ratchet wheel and the successive contact 'pieces 25. Q5", 25C, etc., in one roiv und similar cont-.1ct pieces in the other three rows, is such that for each advance of the ratchet wheel one step, the contact Wipers corresponcling to euch ron' will be moved from one Contact into engagement with the next succeecling Contact. The contact Wipers 3 4 to 37 inclusive, are in pairs, the tivo members oi", each pair being in electrical Contact, but each pair being insulated from the shaft end other conducting parts of the structure by insulating bushings 32, 33, adopted not only to bind and to space the contsct Wipers, Hut also to center them in e well-lmown manner. rlhe ends of the the latter in this instance carrying a ratchet wipers to make contact respectively withtheiirst group of contact pieces, vand so on. Energization ofthe magnet coils 8 and 8a aix-,any time, will releasethe ratchet wheel 13-unless the magnet coils l and 1 are also energized.v `Upon such releaseof Wheel 13, the contact wipers return to normal position, out of engagement with any contact pieces, and the contact betweeen the spring 19 and the contactl piece 18, which remains established so'long as the wipers are out of their normal position, is broken.

The operation "of the circuit and devices shown in Fig. 1 is .briefly as follows: Assuming that a subscriber at substation telephone 43 desires .to make a call, he takes his telephone from the hook, closing the circuit through the -substation telephone, thus by current from battery 67 energizing relays 61 and 53. Armature and contact of relay 6lv now permit current from battery 67 to flow througharmature and contact of relay 64 and thence through magnet 1 and interrupter 66, thus energizing magnet 1 and stepping the set of selecting contacts into connection with the first set of waiting contacts,v28b, 27 b, 26", 25"; current from battery 67A through relay '64, energizes relay 64,'

opens the circuit previously existing through magnet 1 and also energizes relay 68; armature 72 of relay68 gives current from battery 67 through wiper 36 and relay 55, energizing relay 55, whichithen by its armatures and contacts interrupts the current through relay 61 and connects the two limbs of the line 41 to the conductors leading to Wipers 35 and 34 which novT are connected through the waiting contacts to conductors 27 and 28 which in turn are connected through the windings of relay 74 to the ytwo poles of theI battery 67; current. therefore flows from battery 67 through the relay 74 to the-substation telephone 43, and return, and relay 75 is energized; armature 75 of relay 74 closes path for current from battery 67 through winding, contact and armature 69 of relay 68, holding relay 68- energized and leaving open the circuit from battery 67 through relay 64 which originally energized relay 68. Armature 77 of relay 74 now gives current to lamp 86, located adjacent to plug 92 and-before a telephone operator. Responding to the callA indicated the lamp'86, the operator listens upon the trunk 28e-27 by the use of her key 91, takes the subscribers order; lifts plug 92,

ing to the operator. that the called party isat his telephone.

When the called station replaces itsv receiver upon the switch-hook, relay 80 is released and lamp 83 is lighted to indicate a disconnect signal; on similar action at. the

calling station, relay 74 is released and lamp 86 is lighted, also to serve as. a disconnect signal; both lamps thus givinv signals to the operator for Withdrawal o thev trunk. switch plug. Moreover, when the receiver at the calling station 43 is thus replaced,4 relay 53 also is released, and its armature and contact give path for current from battery 67, through contact of 19 `and 18 and. magnet v8; relay 53 has been energized continu o'usly from the closure of the substation telephone circuit, and contact 19-18 is an off# normal contact pair which was closed by the first motion of the rotary part of automatic switch 100; the circuit now closed bythe replacement of the telephone receiver energizes magnet 8 and releases the rotary part of the automatic switch 100; the spiral spring 14 shown on ratchet wheel 13 (Fig. 1) restores the rotary part of the switch to normal, opening contact 19-18 and releasing magnet 8. -All parts are now in their original condition of rest, and are ready for another call. However, if the trunk connected tothe first set of waiting contacts 28D, 27", 26h, 25h had been in use by' another subscriber, relay 68 would have been found energized, and current would notl have passed from battery-67 through relay 64, wiper 37, waiting contact 25h, conductor 25, and contactand armature 69 back to battery; then rotary interrupter 66 would have continually released and energized magnet 1 until in the progress of the rotary part of vthe switch the selecting contacts had come into contact lwith a non-busy set of waiting contacts, as until suchtime circuit through relay 64 could not be completed and magnet 1 could not be permanently released. l/Vhen such non-busy trunk was encountered relav 64 would be energized and magnet l would be permanently released; therefore the motion of the rotary part of the automatic switch must progress until the first non busy trunk is encountered, and must be arrested there, connecting the calling line to that trunk, and lighting the calling signal operator handling the calls for a telephone line anda group of trunks, will remain 'inactive when said telephone line is not active in a call originated by itself; will immediately select the irst idle trunk from said group of trunks when said telephonev vline originates a call, connecting the telephone line t'o that trunk and setting the calling signal' for the operator handling the trai'i'c of that trunk; and further will dise connect immediately upon the replacement of the receiver upon that line, releasing the trunk from thatline.

1n Fig. 2 is shown diagrammatically the arrangement of a complete exchange for seven' telephoner lines, six trunks and three operators," the numberv of each unit being made small to simplify the drawing; to simplify the drawing further, only the essential features of the apparatus are shown, and only'one line is used to indicate the -complete circuits of the element, although it is understood that the telephone lines may be metallic circuits, the plugs and multiple jacks may have three conductors, and the trunks may have four conductors, all as shown'in Fig. 1. The apparatus of the trunk also is included in lthe simple lineshown. Automatic switches are represented at 101', 102, 103,104, etc.,"connected tele-l phone lines are representedby 111, 112, 113` 114, etc., and connected substation telephones are represented by 121, 122, 123, 124, etc. The set of selecting contacts is represented by'131, 132, ctc., and the sets of waiting contacts by 151, 161, 1171, 152, 162, 172, etc. Branch conductors 211, 212, 213, etc. extend fromthe telephone lines, from a point within the central oflicefto the lmultiple jacks of the switchboard which is designated as a whole 259; Trunks 250, 260, 270, etc., connect the automatic switches with` the switchboard," terminating in plugs at the switchboard'end and terminating at the other end in the waiting contacts of the automatic switches, each trunk being multiplied through corresponding contacts of all the switches'. v'lheswitchboard is divided also into three divisions, assumed to be adapted to be occupied by three' operators',

and designated 267, staand 269.

r'l`he"o}' erationvof the system is as follows: The `first call, say from substation telephone 1.23, operates automatic switch 103, moving selecting contacts 133 into connection with 66 waiting' contacts 153. and trunk 250thus is selected, switching'the call to plug 251, upon operator 267. Before disconnection of this call, another call, say from substation telephone 122, over line 112,'act1'1ating'switch 102, would move selecting contacts 132i into connection with waiting'contacts 152, but

as the trunk connected therewith is already' in use, bythe design of the switch 102 the" selecting contacts 132 would be passed one step farther, to waiting' contacts 162, and would stop there, connecting the calling line to' trunk 260, whose plug 261 is before oper# 'ator 267. Anthrd call, originated before the disconnection `of either of the. two calls described-in detail, would find trunks 250 and 260 both busy and therefore would be switched to trunk 270, before operator 268; but were the first call disconnected before the third call was originated, said third call would' find trunk 250 idle and would be switched to operator 267. It is seen therefore-that with this systeln of trunking inf comlng calls, all calls are assigned to' the first position, 267, of the switchboard,until all the trunks upon that'position are busy, and that any calls in excess of the`trunk capacity 'of the firstl position are switchedv to the second position of the switchboard', but that should any trunk or trunks on4 the first position become idle the next calls are Thereforeit placed upon those idle trunks.

condition of all trunks to the first position being busy; to interpret this statement'into other words, no business issent to the second operator until the first operator is working to her-full eiiici'ency and capacity, it being assumedthat the first operator hasv been given a number of trunks which, from observation, will keep her eiliciently busy, and no more. It will be seen also from the diagram that no call will be switched to the third position of the switchboard until such time asall trunks to both the first and second positions are busy, and that therefore as long as the entire trafc of the exchange can be handled by two operators, all calls will `be automatically switched'to those two positions, regardless of how1 many additional positions may be equipped upon that switchboard'.

In the mechanical design of the automatic switches, economy requires that the parts be as few and as simple as possible, and this in turn limits the number of sets of waiting contacts which are 'placedupon each auto? to be extended until the number of trunks c reaches twenty-five, and until the telephone lines, unlimited numerically, produce'such an amount of trafic as cannotl be handled over the twenty-five' trunks; at this point it is possible to increase the number of trunks by either of two methods: first, to substitute larger switches, each accommodating, a larger number of sets of waiting trunk contacts; second, to install additional switches* similar to the irst, but connected with a separate group of trunks. The second plan is illustrated diagrammatically in Fig. 3.

In .Figi 3, automatic switchesv 101, 102, etc., represent the switches serving the irst group oftrunks, 250, 260,.etc., the individual switches ofthe group4 belonging -individulally to the telephoney lines 111, 112, etc.,

switchboard 259 .are located also groups 2 5, .276, etc l of plugs 251, 261, 351, etc., belonging 4to lthe individual trunks of the trunk groups, as diagrammatically shown. Trunk 250 is the irsttrunk of its group and termif nates upon a plug .251 of plug group 275;

trunk 350. is Vthe first trunk of its trunk groupand terminates upon a plug 351 of lug groupv 275; itis seen also that all of the lirst trunks of;4 lall the trunk groups terminate in plug group 27 5. Likewise, trunk 260, the second of its trunk group, terminates upon a plug 261, in plug group 276; it is seen also thatv all yof the' second trunks of all of the trunk groups terminate in plug group 276,- which therefore may be termed uthelsecond plug group. Likewise, theA third trunks of` all groups terminate in plug` group 277, `the third plug group, and'. so through.

out the switchboard. `As the number of trunks in, each trunk .group` is limited by the mechanical construction of the automatic same trunk group, when the existence of the switch to twenty-five, it follows that there will be twenty-five plug groups 275, y276, etc.; these plug -groups will occupy the en-- tire switchboard 259, regardless of the extentof said switchboard or of the number'of operators to be accommodated by it.

The first call from any group of substations will be sw-itched to the irst trunk of 'the trunk group serving those substations, l and therefore will be switched to plug" group 275, thel irst plug group. Further, all calls from all trunk groups will be switched to said iirst plug group until such time as two calls exist simultaneously in the prior call in that trunk group will cause'the s'econdtrunk of the group to be `selected by the later call and thus the second of the two simultaneous .calls will be switched to the q second plug group 276. In like manner, the

first two `pluk 'groups will receive all calls until the tra c' of the switchboard becomes so great -thatthree simultaneous calls exist in one trunk group, when the 4last-of the calls will be switched to the third trunk of that trunk group and therefore to the third plug group. Thus in Fig. 3, as in Fig. 2, the 'traiic of the entire exchange is automatically switched to the rst plug group until the'traiic exceeds the capacity of that pluggroup, when the sur lus is sent to the second plug group, the tra c being then sent to those two lplug groups until it exceeds their capacity, when the surplus is 'sent to the third plug group, and so on until inthe periods of maximum traffic of the exchange the entire switchboard is assumed tobe utilized.,

In the arrangement of ,parts shown in Fig. 3, the number of pluggroups 275,276, etc., is twenty-ive by limitation 'of automatic switch construction, but the number of plugs in each groupis unlimited, being governed only'T by the size of the telephone exchange. y The distribution of the plug groups among operators therefore becomes a feature to be considered. In a small exchange, say 100 trunks, four plugs in each,

plug group, the first operator on duty. could handle probably ten trunks, being the first two plug groups and two plugs of the next plug' group; the second operator on duty would handle the remaining two plugs of the third plug group and also the fourth and fifth plug groups, etc. In an exchange of 250 trunks, 10 trunk groups, 10 plugs in each plug group, each plug group probably would be equal to an operators capacity, but if nine trunks were the capacity of the first operator on duty, she would be given nine plugs from the firstplug group, the second operator on duty would be given the remaining plug ci the first group and eight plugs from the second plug group, the third operator on duty would be given the remaining two plu s from the second plug group and seven p ugs from the next plug group, etc. It is seen therefore that each operator can be given justenough work to utilize her capacityl economically and etilciently, and that allsurplus traiic will be lshifted to the `next operator in order, re-

gardless of vwhether in such disposition of trailic the first operator handles several plug groups or the first plug group requires several operators..

In the description relating to Fig'.` 3, it is assumed that the traffic arising in the many substations will be distributed equally, or approximately so, among the several trunk groups; to secure and maintain such distri bution, the iirst intermediate distributing frame, 50, is shown in Fig. 4. In the construction of the switchboard, a fixed number of plugs is given to each operators position,

' which fixed number by design should be as great as the number of trunks ever required to be ternnnated for that operator-s use; in

araches lacing the switchboard in service, the num- `:er of active trunks required by the operator to utilize her capacity efliciently, may not coincide with the number of trunk plugs provided when building the switchboard, may vary with the individuality ot the operator, and may vary from time to time with some variation in the nature of the traffic. To secure economical, convenient and dexible distribution of' the active trunks among the operators positions, the second intermediate distributing frame is provided at 6() in Fig. 4, which distributing board also provides facilities for the new grouping' of trunks andt plugs necessary to follow implicitly. the plan shown in Fig. 3, when by the growth of theexchange it is necessary to install an additional trunk group and thus to include'an additional plugin each plug group; by means of the second distributing frame it is possible also to connect upon one plug two or more sets of conductors from the .waiting contacts of the automatic switches.' The main distributing board 70, is an adjunct of every modernv telephone exchange, and is for that reason included i in Fig. 4f. Each line, trunk, or other circuit in Fig. 4, is represented as a unitby a single line, except that in the distributing frame jumpers the conductors are separated to show the number of conductors involved and also that by reference to similar'numbers of Fig.' l, the'parts of the circuits Inay be more readily identified. Main c listributing frame jumpers are numbered 7 00; first intermediate jumpers 500; second intermediate jumpers 600. These intermediate distributing frames serve the further purpose of permitting the isolation of any part of the apparatus which may become defective.

To recapitulate the system of `selection and distributing frame connection: All calls are switched to selected trunks, certain trunks being so placed in the automatic switches as to receive the calls in precedence over other trunks, and thus a relation is established between the trunks of any group which may for convenience be termed an order of precedence. ln each group, those ftrunks having priority over others in the matter of receiving calls may be referred to as being of a higher order of precedence...

Calls received by trunks are carried to plug groups on the -multiple switchboard in a f method of distribution governed by the second intermediate distributing frame 60, and in this distribution the earlier calls are collected to one of the plug groups, and thus the plug groups may be said also to havev an order of precedence.- Plug groups are.

located adjaccntto each other in their order of precedence, and thus the object is accomplished of having all calls concentrated upon `one portion ofthe switchboard and plugs and at its other end with homologous' waiting contacts in all of said automatic switches, said trunks having among there` selves an order of precedence in receiving' calls and a grouping of their said plugs adapted to terminate in one group those trunks having the highest order of precedencein receivingcalis and in other plug groups those trunks having other orders oi precedence; substantially as described. l 2. In a telephone system, the combination of telephone lines and substation telephones automatic swtches connected with said telephone lines; multiple jacks connected,withI said telephone lines; plugs ladapted to con.-` nect with said multiple jacks; and trunks connecting said plugs with said automatic switches, said trunks being so arranged that certain trunks have precedence over others in receiving calls, and the plugs being so grouped as to terminate in one plug groupI those trunks having the highest order ornA precedence; substantially as described 3. ln a telephone system, the combination of telephone lines and substation telephones; an automatic switch for and connected with each of said telephone lines; waiting contacts in said automatic switches; multiple jacks connected with said telephone lines; plugs adapted to connect 'with said multiple jacks; and trunks forming a plurality of l trunk being connected at one end with one of the plugs and at its other end with all.

homologous waitingcontacts of the autos.

matic switches pertaining to its trunk group, the trunks of eich group being ar-` ranged so that they will have among themselves an order of precedence in receiving calls, and said plugs being so' grouped as to terminate in one plug group those trunks in all ofthe trunk groups which have the highest order of precedence and in other plug' groups those trunks er" other orders oit.k precedence; substantially as described.

4. .ln a telephone system, the combination of telephone linesl and substation telephones an automatic switch for andconnected with, each of said telephone lines; multiple jacks connected with. said telephone lines; plugs v adapted" to. with said multiple jacks and forming a plurality of plug. roups; and trunks;v forming a plurality oi: trunk groups and connecting said plu s with said automatic switches, the' trunkso each group beingso arranged that they will have among themselves an order of precedence in receiiing calls, and the plugs .being so .gnouped as to terminate 1n one plug group t.

ose trunks in all of the trunk groups which have the highest order of precedence and' in other plug groups those trunks of o .-er orders of precedence; substantially as described.

5. Inf vtelephone system, the combination of telephone lines and substation telephones; an automatic switch for each of said telephone lines; a distributingl frame; terminals on said distributing frame connected to said lines; terminals onsaidy distributing frame connected to said automatic switches;l j -umpers in said distributing frame adapted' to lconnect together the terminals `of any line and the terminals of any automatic switch; multiple jacks connected to said telephone lines; plugs adapted to: connect with. said multiple jacks; and trunks. connecting said multiple jacks with said autoniatic switches; substantially as described.

6. 4In a telephone system, the combination vof telephone lines and substation telephones;

an automatic switch for and connected 'with each of said telephone lines; multiple Jacks connected with said telephone lines; plugs adapted to connect with said multiple jacks; a distributing frame; terminals onA said distributing frame connected with said plugs; terminals on said distributing frame connected with said automatic switches.; and jumpers in saidl distributing frame adapted connect together the terminals 'of any. plug and the terminals of any automatic-l switch; substantially as described.

7. 1 In a telephone system, the combination of telephone lines and substation telephones;

an automatic switch for each of saidl tele. phone lines; a distributing frame; terminals on said distributing frame'connected to said lines: terminals on .said distributing lframe.A connected to said automatic switches; jump- -ers in said distributing' f'rame adapted to connect together the. terminals of any line and the. terminalsot' any automaticswitch; multiple jacks connected to sald' lines; plugs adapted to connect withsaid multiple jacks;

another distributing frame; terminals on said latter distributing frame connected with said plugs; terminals on said latter distributing frame connected with said automatic switches; and jumpers in said latter distributing frame adapted -to* connect together the terminals of any plug and the terminals nii any automatic switchg; substgtialjly as described;

' est order 4.of preceden the highest order yof tially as described.

e. 1a a telephone System, the comunales.

of telephone lines and substation telephones; automatic switches ccnnected with said telephone lines; waiting contacts in said automatic switches; other lines; multiple jacks connectedwith said Vothei;lines@ plugs adapted toconnelct with said i`nul tiple jacks l:l and .trunks eacli'fc'onnected at :one en'd withpne-of said.plugs.andv at the, thei end with homolcgous'jwaiting ,'contacts'ii-'i all ofits corresponding automatic switches, 75 said-.trunksv having i rig' gtlem'selas l:an order of precedence'in 'Ying-'Calls fin/dia grouping 0f Said Plugs@ rtdgte tlria in one group those trlink ,having tlie'hi'gh'- ci rcceiyingcalls, 30 and `in othergplug .grou Mth-l e trunks haiting yother orders of pyrecderceip 9. In a telephone syste he combination of telephone lines ubs'ta'tionf l"tels-lu phones automatic switches connected with 35' saidtelephcne, lines; other lines# multiple.- j acksv connectedA withz saidfothe'r. lines adapted to connect with said-fniultiple" "acks; and trunks connecting said yplugs `witllisaid;f automatic switches, said trunks bingf vso 90' arranged that certain, trunks hayeprecdence over lothers in receiyingcalls, fnd the plugsbeing .so groupedfasytiterniinate in one plug group theseA trunks having? 1:

precedence t, "subfs'tii- 95 10; yIn a` telephone systeme the combination of telephone lines and'subStationQtelephones; an automatic lswitch ffor'fandion-'t nected with each of saidtelephoneflines; waitingcontacts in said automatici switches other lines: multiple jacks connected ,with said other lines; plugs adapted tibc'onnected` with said multiple jacks; and'itrur'iksf: forming a plurality of groups7` each group 105 having a. group of automaticswitches tpertaining theretoeach trunk'b'eing connected atone ,end withvone ofthe plugs and? at .lits other endwith all homologous-waiting tcon-ftactsof Vthe vautomatic switches'pertaining 110 to itstrunkgrougthe 'of eachl group being arranged so". that they will lia'ueair'ring themselves-an order o'f precedence'in rciving calls,` and said plugs being v'so",gir'f-ii'1pedas'to terminate in one' plug groupthose 115 trunks in allot the trunk groups `wliiclrhave thev highest' order of precedencel and' iii other plug 0'roups those trunks of other orders" of prece( ence; substanti ally described." f "f f' i;

, 1.1; In ya telephone 'systemftll'e 'combina- 120 tion 4.of telephone` lines andfsubstatioirl telephones; an automatic switch fo'ra"1id connected with each offsaid' telephone?lines; other lines' multiple 'iackfs connectedwith said other lines; plus adapted" to jcp'n'nec't 125 with said multiple jaisgand' Q'rnii'ngf-afplu-H rality l01.pliugg groups;v andI trunksffornring primary oftfunk groups-ad @anteilig trunks-'of `each grc'upv snarrnged'that 130 they will have among themselves an order Signed by me at Pittsburgh,'county of of precedence in receiving calls and the Allegheny, and State of Pennsylvania, in 10 plugs being so grouped as to terminate in the presence of two Witnesses.

one plug group those trunks in all of the trunk groups which have the highest order A SIDNEY HAND BROWNE' of precedence and in other plug groups those Witnesses: v

trunks of other orders of precedence; sub- A. H. MORAWECH,

stantially as described. B. H. SHRYocK.

Copies of this patent may be obtained for ve cents each, by laddressing the Commissioner of Patents, Washington, D. C. 

